Porcine epidemic diarrhea virus is a member of the family Coronaviridae, genus alphacoronavirus. It is a positive-sense, enveloped, single-stranded RNA virus. Porcine epidemic diarrhea (PED) was first observed among English feeder and fattening pigs in 1971. During the 1980s and 1990s, PED was prevalent throughout Europe, in countries such as Belgium, England, Germany, France, the Netherlands, and Switzerland. These outbreaks were relatively mild and could be controlled. Currently, there are no indications that PEDV is present in Europa. Severe PEDV outbreaks with high mortality are common in Asia, where it has probably become epidemic in some areas. China has seen a large increase in outbreaks since 2010 which has been attributed to the emerging of new strains, and currently PEDV is one of the main pathogens giving large economic losses in the swine industry in Asia. An Asian-like PEDV strain was for the first time introduced in the United States in April 2013 and has spread to Canada and Latin America. PEDV is most commonly transmitted via fecal-oral contact with infected swine, and may also be introduced by contaminated equipment, fomites, or personnel. Infected pigs, dirty boots, clothing, hands, equipment, or trucks can spread the disease. But there are also indications that PEDV can be transmitted through air. Sanitation and biosecurity are the best means of prevention.
In pigs, severity of disease is variable and dependent on the epidemiologic status of the herd. The primary, and often only, clinical signs are acute watery diarrhea and vomiting. In naïve animals, vomiting, acute watery diarrhea, and loss of appetite in pigs of all ages can be observed; morbidity approaches 100 percent. Particularly suckling pigs are very susceptible, and they typically display watery diarrhea, dehydration, and metabolic acidosis with mortality typically between 50 and 80 percent. On the other hand, feeder and grower pigs display diarrhea, anorexia, and depression with high morbidity, but low mortality (1-3 percent). When PEDV-infected swine are introduced to a naïve premises, clinical signs typically appear within 4-5 days. PEDV cannot spread to humans.